Index: frontend/node_modules/react-app-polyfill/ie11.js
===================================================================
--- frontend/node_modules/react-app-polyfill/ie11.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
+++ frontend/node_modules/react-app-polyfill/ie11.js	(revision 9af201e94b5a79beb92a30858fc54de4bc3b9449)
@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+'use strict';
+
+if (typeof Promise === 'undefined') {
+  // Rejection tracking prevents a common issue where React gets into an
+  // inconsistent state due to an error, but it gets swallowed by a Promise,
+  // and the user has no idea what causes React's erratic future behavior.
+  require('promise/lib/rejection-tracking').enable();
+  self.Promise = require('promise/lib/es6-extensions.js');
+}
+
+// Make sure we're in a Browser-like environment before importing polyfills
+// This prevents `fetch()` from being imported in a Node test environment
+if (typeof window !== 'undefined') {
+  // fetch() polyfill for making API calls.
+  require('whatwg-fetch');
+}
+
+// Object.assign() is commonly used with React.
+// It will use the native implementation if it's present and isn't buggy.
+Object.assign = require('object-assign');
+
+// Support for...of (a commonly used syntax feature that requires Symbols)
+require('core-js/features/symbol');
+// Support iterable spread (...Set, ...Map)
+require('core-js/features/array/from');